HP
RM1-8615-020CN
is compatible in the following HP Models:
HP LaserJet Pro MFP 500 series
HP LASERJET PRO MFP M521DN - A8P79A
HP LASERJET PRO MFP M521DW - A8P80A
HP LaserJet 500 Multifunction Printer series
HP LASERJET MANAGED MFP M525FM - L3U59A